Gas detectors for ATEX Zone 1 are located in a flameproof enclosure,
EEx d

The shell is such that ignition and
combustion within the shell of a potential explosive gas mixture is
not propagated to the explosive mixture outside the enclosure and
the enclosure can thus endure the resulting explosion pressure
without damage.

In Zone 1

,
one can expect an explosive atmosphere to occur during normal
operation but the presence of it is relatively
short.

The equipment shall not be a source of
ignition in normal operation or when an error occurs.

Gas detectors for ATEX Zone 2 are of the
design Non-sparking EEx nA

EEx nA is a non-sparking

piece
equipment.

In Zone 2, you need not count with an
explosive atmosphere to occur during normal operation, and if it
should occur, which is probably rare

it is of
short duration.

The equipment shall not be a source of
ignition during normal operation.